Avoiding Early Complications After Metal-on-Metal Hip Resurfacing: The Technical and Conceptual Aspects of “Bailing-Out” to Total Hip Arthroplasty

Abstract

Metal-on-metal hip resurfacing (MOMHR) is gaining in popularity as a viable alternative to total hip arthroplasty (THA) in the treatment of advanced osteoarthritis in the younger patient. This is due to both the bone sparing nature of the procedure and the low wear rates of a metal-on-metal articulation combined with a high range of motion caused by the large sized femoral head. Mid-term results in Europe and Australia have been encouraging with most available implants, and early results in the United States are starting to emerge as comparable. There have been, however, some poor early results reported in the US with an alarming array of early complications. Our understanding of the risks and complications of MOMHR are continuously evolving. The surgeon must be able to recognize when completion of a planned MOMHR will place the patient at an unacceptably high risk of early failure. In this report, we examine a consecutive series of patients of 2 surgeons at a single United States institution indicated for MOMHR and discuss the reasons for converting intraoperatively from MOMHR to THA. All patients scheduled for MOMHR from March 2005 to March 2009 were included in the study. During this time, 189 MOMHRs were scheduled and 31 became intraoperative bail-outs to THA. In the bail-out group, 23 were male and 8 were female. Average age was 53.2 ± 8.5 and average BMI was 30.2 ± 6.4. The most common diagnoses were osteoarthritis (65%), dysplasia (16%), and avascular necrosis (AVN) (10%). In the MOMHR group, there were 105 males and 40 females; average age was 50.2 ± 8.8, average BMI was 27.9 ± 4.8, and the most common diagnoses were osteoarthritis (74%), AVN (10%), and dysplasia (9%). The bail-out rate was 16.4%. The most common reasons for bailing out were a large cyst (39%), poor bone quality (19%), femoral head or neck deformity (16%), implant size mismatch (16%), and varus neck (6%). The bearing surfaces used in the bail-out THAs were mostly metal-on-metal (75%), but also included metal-on-poly and oxinium-on-poly. Optimizing survivorship for MOMHR occasionally requires bailing-out to THA. Patients must understand that THA remains the gold standard and should not be disappointed. Surgeons should understand when bail-out is necessary and inform patients about this possibility. Completion of MOMHR in the above situations can lead to early failure and reduced survivorship.